The invention is generally related to an external mirror for motor vehicles, especially for trucks or buses. The invention is more particularly related to an external mirror having unitary housing design to which various elements are readily secured.
External mirrors of various constructions have been made. Typically, external mirrors include a housing integrated with a vehicle body in some way, a mirror plate, and a swivelling mechanism inserted between the mirror plate and the housing for positioning and securing the mirror plate in an adjustable manner relative to the housing. The housing is typically an injection molded part made of heavy plastic, which is generally shaped as a trough, to which mirror elements are installed over corresponding mounting points. In order to provide the housing with necessary stability, expensive ribs and reinforcements are necessary. Moreover, the mounting pointsxe2x80x94for instance, screw collets, entry borings, and the likexe2x80x94are installed for additional mirror parts by means of relatively costly molding tool work on the housing.
For large trucks and bus mirrors, very often tubular or plate designs are employed for the support means of the external mirrors, which are directly integrated with the mirror holder extending from the vehicle body (see, for example, EP 0 590 510 A1). The housing serves in this case only not as a cover for the back side of the mirror plate and the swivelling mechanism, but also as an aerodynamic sheathing for the external mirror. Such designs are extremely expensive and heavy.
Known multiple unit mirrors employ a complex grating type tube design, upon which the housing is simply set as a sheathing thereover. The mirror, is thus weighty and can only be produced at a high cost. In particular, the molding equipment for the production of the sheathing portion is very complex and hence expensive.
It is accordingly an object of the invention to provide an external mirror addressing and solving the above drawbacks and others of the prior art.
It is an additional object of the invention to create an external mirror that is simple and inexpensive to manufacture and assemble, and a corresponding method of assembling the external mirror.
It is another object of the invention to provide a mirror that is stable and resistant to vibration.
These objects and others are achieved by the features and corresponding method steps described and explained below. The invention provides a housing that is a self supporting, integral shaped piece from a single foam core with a reinforcing layer that covers the core. The invention provides a simple manufacture, high shape stability, minimum vibration sensitivity, and low weight. Very complex basic housing shapes can be made, as well as very large housings. These advantages will be discussed in detail below with reference to particular preferred embodiments.
Polyurethane material has been selected as a preferred plastic substance for the foam core and the reinforcing layer which is applied thereon. It suffices for the installation of the mirrors and for the related swivelling mechanism, generally, to allow for a basin shaped reception recess in the housing. In this design, the mirror plate is installed with the swivelling mechanism and, for example, affixed to the housing for a long term period by plastic tapping screws or an appropriate adhesive. Special screw collets or penetrating borings, as used in conventional devices, are not necessary, substantially reducing the technical forming process.
Due to the filling of the housing by foam material, it is possible, even during the formation of the housing, to embed within the foam core, for instance, fittings for the attachment of the housing on to the body of the motor vehicle, holder bases for the fastening of the swivelling mechanism to the housing, and cable and/or empty tubing for the electrical system, the positioning control, and the heating of the mirror plates. This too reduces the amount of the production costs for the external mirror itself and the expense of the final mounting on the vehicle. The housing can also be penetrated by an opening through the foam core, so that the housing is mountable on a retaining arm for the mirror.
The multiple unit mirror embodiment according to the present invention includes a self supporting housing, which not only serves as the support structure, but also as the sheathing of the mirror plates within the respective swivelling mechanism. The housing can be made with a relatively simple molding set up, whereby the molding costs are substantially reduced. Because of its integral structure and the stability of shape along with low response to vibration provided by the integral structure, the corresponding multiple unit mirror is well-suited for use on vehicles such as busses.